ASA 126th Meeting Denver 1993 October 4-8

4pAA1. Subjective and objective parameters of sound within fabric
structures.

An investigation of acoustics in 15 circuses with fabric roofs has been
carried out. Objective acoustical parameters (reverberation time, clarity C[sub
80], and others) have been measured and questionnaires from the audience in the
circuses have been obtained. Features of circuses acoustics are the decrease in
reverberation times at low frequencies, echo (in halls with impervious fabric
roofs), and high levels of background noise. The background noise levels in
circuses before a performance were equal L[sub A]=46--56 dBA. The questionnaire
contained subjective acoustical attributes: Timbre, balance, reverberance,
spaciousness, echo, loudness, clearness, audibility of background noise,
background noise affect on speech legibility, and others. Average mark
estimates and results of measured noise level in halls (L[sub A]) have been
subjected to factor analysis. Three factors have been extracted that can be
interpreted as (1) overall acoustical impression of the music sound in a
circus, (2) disturbing influence of the background noise, and (3) clarity of
music and speech sounding.